#!/usr/bin/env python3

import os
import shutil

import common
from shell_helpers import LF

class Main(common.BuildCliFunction):
    def __init__(self):
        super().__init__(
            description='''\
Build the Linux kernel.
'''
        )
        self.add_argument(
            '--config', default=[], action='append',
            help='''\
Add a single kernel config configs to the current build. Sample value:
'CONFIG_FORTIFY_SOURCE=y'. Can be used multiple times to add multiple
configs. Takes precedence over any config files.
'''
        )
        self.add_argument(
            '--config-fragment', default=[], action='append',
            help='''\
Also use the given kernel configuration fragment file.
Pass multiple times to use multiple fragment files.
'''
        )
        self.add_argument(
            '--custom-config-file',
            help='''\
Ignore all default kernel configurations and use this file instead.
Still uses options explicitly passed with `--config` and
`--config-fragment` on top of it.
'''
        )
        self.add_argument(
            '--config-only', default=False,
            help='''\
Configure the kernel, but don't build it.
'''
        )
        self.add_argument(
            'extra_make_args',
            default=[],
            metavar='extra-make-args',
            nargs='*'
        )

    def build(self):
        build_dir = self.get_build_dir()
        if self.env['initrd'] or self.env['initramfs']:
            raise Exception('just trolling, --initrd and --initramfs are broken for now')
        os.makedirs(build_dir, exist_ok=True)
        tool = 'gcc'
        gcc = self.get_toolchain_tool(tool)
        prefix = gcc[:-len(tool)]
        common_args = {
            'cwd': self.env['linux_src_dir'],
        }
        ccache = shutil.which('ccache')
        if ccache is not None:
            cc = '{} {}'.format(ccache, gcc)
        else:
            cc = gcc
        if self.env['verbose']:
            verbose = ['V=1']
        else:
            verbose = []
        common_make_args = [
            'make', LF,
            '-j', str(self.env['nproc']), LF,
            'ARCH={}'.format(self.env['linux_arch']), LF,
            'CROSS_COMPILE={}'.format(prefix), LF,
            'CC={}'.format(cc), LF,
            'O={}'.format(build_dir), LF,
        ] + verbose
        if self.env['custom_config_file'] is not None:
            if not os.path.exists(self.env['custom_config_file']):
                raise Exception('config fragment file does not exist: {}'.format(self.env['custom_config_file']))
            base_config_file = self.env['custom_config_file']
            config_fragments = []
        else:
            base_config_file = os.path.join(self.env['linux_config_dir'], 'buildroot-{}'.format(self.env['arch']))
            config_fragments = ['min', 'default']
            for i, config_fragment in enumerate(config_fragments):
                config_fragments[i] = os.path.join(self.env['linux_config_dir'], config_fragment)
        config_fragments.extend(self.env['config_fragment'])
        if self.env['config'] != []:
            cli_config_fragment_path = os.path.join(build_dir, 'lkmc_cli_config_fragment')
            cli_config_str = '\n'.join(self.env['config'])
            self.write_string_to_file(cli_config_fragment_path, cli_config_str)
            config_fragments.append(cli_config_fragment_path)
        self.sh.cp(
            base_config_file,
            os.path.join(build_dir, '.config'),
        )
        self.sh.run_cmd(
            [
                os.path.join(self.env['linux_src_dir'], 'scripts', 'kconfig', 'merge_config.sh'), LF,
                '-m', LF,
                '-O', build_dir, LF,
                os.path.join(build_dir, '.config'), LF,
            ] +
            self.sh.add_newlines(config_fragments)
        )
        self.sh.run_cmd(
            (
                common_make_args +
                ['olddefconfig', LF]
            ),
            **common_args
        )
        if not self.env['config_only']:
            self.sh.run_cmd(
                (
                    common_make_args +
                    self.sh.add_newlines(self.env['extra_make_args'])
                ),
                **common_args
            )
            self.sh.run_cmd(
                (
                    common_make_args +
                    [
                        'INSTALL_MOD_PATH={}'.format(self.env['out_rootfs_overlay_dir']), LF,
                        'modules_install', LF,
                    ]
                ),
                **common_args
            )
            # TODO: remove build and source https://stackoverflow.com/questions/13578618/what-does-build-and-source-link-do-in-lib-modules-kernel-version
            # TODO Basically all kernel modules also basically leak full host paths. Just terrible. Buildroot deals with that stuff nicely for us.
            # self.rmrf()

    def get_build_dir(self):
        return self.env['linux_build_dir']

if __name__ == '__main__':
    Main().cli()
